1. Field of the Invention
The present invention relates to a method for modifying a program of a magnetic tape unit such as a streamer for backing up data.
2. Description of the Related Art
In a magnetic tape unit such as a streamer for backing up data, various programs for operating the magnetic tape unit are stored in a ROM and are executed by a CPU. In this case, such ROM is divided into a removable EPROM and another ROM to accommodate a change in specification of the program and an occurrence of failure after shipping the magnetic tape unit. That is, part of the programs whose specification might be modified are stored in the EPROM and another part is stored in the other ROM. The EPROM is removably attached to a socket without soldering and the other ROM uses a ROM and the like in the CPU.
When a specification of a program is to be modified, the EPROM is removed from the socket to rewrite the program in the EPROM as a program whose specification has been modified and is then attached again.
However, it is cumbersome to remove the EPROM from the socket to rewrite the program and then to reattach it into the socket. Moreover, since the magnetic tape unit is usually built in a case, it is necessary to disassemble the case, which involves cumbersome work.
A method of using a flash memory which is electrically erasable instead of an EPROM and of providing a special connector in front of the magnetic tape unit has been considered. When a specification of a program has been modified, the contents of the flash memory are erased and the program is transferred by serial communication from the outside via the connector to write the program into the flash memory. With this method however, although a case in which the magnetic tape unit is incorporated does not have to be disassembled, a special connector needs to be provided. This increases the cost and causes problems wherein the connector may be damaged and be illegally used since it is readily accessed by an operator and is broken by static electricity of the human body.
When a specification of a program has been modified, a method of transferring a program from a host computer (hereinafter referred to as the host) utilizing an interface such as SCSI, which the magnetic tape unit has between the host after erasing the contents of the flash memory to rewrite the program to the flash memory, is conceivable. According to this method, however, the host must read the program, so that a special application program needs to be provided in the host.